Fonology

Fonology, often spelled phonology, is the branch of linguistics that studies the systematic organization of sounds in languages. It focuses on abstract sound units called phonemes and the rules that govern their distribution and patterns, rather than the physical properties of speech sounds (the domain of phonetics). Fonology also analyzes suprasegmental features such as stress, tone, and intonation, and how they interact with segments to affect meaning.

A central distinction is between phonemes, which are contrastive sound units, and allophones, their non-contrastive realizations. Phonology analyzes how phonemes are organized into inventories, how they combine into syllables and sequences (phonotactics), and how rules or constraints shape their positions across contexts. Analyses typically distinguish underlying representations from surface forms and study processes such as assimilation, dissimilation, and vowel length or tone patterning.

Historically, phonology has evolved from structural and generative theories toward formal models such as optimality theory and autosegmental representations. Early natural phonology emphasized innate simplification processes; later generative phonology posited rule-based derivations from underlying forms. In the late 20th century, optimality theory framed phonology as constraint-based evaluation of surface forms. Contemporary work often integrates multiple frameworks and uses cross-linguistic data to compare systems.

Phonology relies on data from linguistic description and fieldwork, using minimal pairs and distributional analysis to identify contrasts and patterns. Applications include language documentation, literacy development, speech technology, and the study of language change. Phonological theory intersects with morphology, psycholinguistics, and cognitive science as researchers seek universal patterns and language-specific variation.